The specified maximum runtime of the job was exceeded

Hi, I have a problem when meshing one scenario. The case is a very big mesh with around 8M nodes. The problem appears when during the meshing process I get the following message:
The specified maximum runtime of the job was exceeded. The simulation run was stopped and potential intermediate results were restored. You can increase the maximum runtime in the simulation control section to enable a complete simulation run. the simulation times are too high for the available core.I don’t know how to decrease the number of nodes and cells to start the simulation under the chosen conditions. I have tried several times to modify the mesh but I don’t know how to do it. if you want to help me I am attaching the link of my project:


You can increase the maximum runtime under ‘Simulation control’:


Currently you have 1e4 = 10 000 seconds. After this clock time elapsed, the computation is stopped. Please increase it so your simulation can perform all the specified iterations.

yes I’ve already tried

Hi matyfalcone,
Just reading your message and looking at your mesh, which has 28.5 million cells, that is really big, so I can imagine why the simulation is not running. I am an newbie Simscale person, but found this information which should assist.

I noticed that there are two parts to this “Conjugate Heat Transfer in a U-tube Heat Exchanger” tutorial which I overlooked twice when I was searching for a solution.

This link Conjugate Heat Transfer in U-Tube Heat Exchanger | SimScale takes you to long webpage where a step by step tutorial takes you though everything, but only scroll down and do not click on the document link on the first page of the tutorial as it will take you to a more high level overview of the processes without all the details.

And at the very bottom of the tutorial is a finished complete working Simulation from Simscale, which should provide you with the answers to reducing the project’s mesh size, if you replicate what Simscale has done. The working Simscale project has a mesh of 3.1Million cells.

I hope the above assist, best of luck with the simulation.

hank you for your answer, I have already followed this tutorial to set up the simulation but if you notice my mesh has a higher number of tubes and a larger size than the one in the tutorial

Hi matyfalcone,
The model you have created certainly has more complexity which has significantly increased project meshing. A courser overall standard mesh with possibly some localised refinement of the mesh will be required to obtain convergence of the simulation.

This link describes a tutorial on a heat sink, with a gradual process of cell refinement for the heat sink using the standard mesh plus surface, region and boundary inflation.

This link provides additional details on the Standard mesher with video & reference to small feature suppression.

My general approach would be to reduce the fineness of the Standard mesh by dialing back the current setting of 5 to say 2 and then generate the mesh. If the mesh stays below say 6 to 8 million cells you should be able to run the simulation, possibly you may need increase the Maximum Runtime in the Simulation Control area. Hopefully, the Simulation will converge, but if it doesn’t, then localised refinement will be necessary.

At times with a coarser meshing the simulation may be halted due to instability and a coordinate provided in the error message of the instability. Then a finer mesh from say 2 to 3 may be required or a specific refinement using a Regional or surface refinement may be necessary to negate the instability. A mixture of a overall mesh size with specific mesh regional & surface refinement is one way to reduce mesh size. Also removing fine details and adjusting the small feature suppression can be considered to reduce mesh size.

It may be worth looking at someone’s simulation that shows a practical application of mesh refinements.
Here is an image of my multiple mesh refinements for a large fan. Basically, you create the Refinements under the Mesh area & set local grid mesh fineness (highlighted green line). Then you create the sphere, box or cylinder regions as highlighted by the red line. Then you can associate each box or sphere or cylinder with the Refinement that was setup.

Again my approach to this learning of meshing has been to look at some successful Simscale produced simulations with mesh refinements to get a practical understanding.

Hopefully this is of some assistance.